compat_ioctl: fix FIONREAD on devices
My final cleanup patch for sys_compat_ioctl() introduced a regression on
the FIONREAD ioctl command, which is used for both regular and special
files, but only works on regular files after my patch, as I had missed
the warning that Al Viro put into a comment right above it.
Change it back so it can work on any file again by moving the implementation
to do_vfs_ioctl() instead.
Fixes: 77b9040195de ("compat_ioctl: simplify the implementation")
Reported-and-tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Reported-and-tested-by: youling257 <youling257@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 7c9a5df..5152c98 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -523,13 +523,9 @@ static int compat_ioctl_preallocate(struct file *file, int mode,
static int file_ioctl(struct file *filp, unsigned int cmd, int __user *p)
{
- struct inode *inode = file_inode(filp);
-
switch (cmd) {
case FIBMAP:
return ioctl_fibmap(filp, p);
- case FIONREAD:
- return put_user(i_size_read(inode) - filp->f_pos, p);
case FS_IOC_RESVSP:
case FS_IOC_RESVSP64:
return ioctl_preallocate(filp, 0, p);
@@ -721,6 +717,13 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd,
case FIDEDUPERANGE:
return ioctl_file_dedupe_range(filp, argp);
+ case FIONREAD:
+ if (!S_ISREG(inode->i_mode))
+ return vfs_ioctl(filp, cmd, arg);
+
+ return put_user(i_size_read(inode) - filp->f_pos,
+ (int __user *)argp);
+
default:
if (S_ISREG(inode->i_mode))
return file_ioctl(filp, cmd, argp);